ity. Growth rates may not have diminished appreciably. If so, this development should not serve as a discouraging factor. It is only by concerted effort to reduce fertility now that reductions in growth rates can be effected in the next generation. It is clear that reductions in mortality can go only so far; sooner or later reductions in fertility, if they occur, will reduce the rate of population growth. To recognize the difficulties involved is not to be pessimistic. On the contrary, there is every reason for optimism as one looks to the future: the increasing awareness of the problem, the increasing inputs into biomedical and social research, and the rapidly developing action programs. However, such optimism must realistically recognize that for the rest of this century, there is every prospect that the world will experience excessive population growth, with its attendant problems.
In general, the economically advanced nations can control excessive population growth within their borders by doing a little more of what they are already doing to lower their growth rates further or even to achieve a zero rate of growth. In the developing nations, however, much yet remains to be done before the control of the population explosion is assured.
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